CN102148492A - Method for acquiring control input signal of subsynchronous oscillation suppression and control device - Google Patents

Abstract

The invention relates to a method for acquiring a control input signal of a subsynchronous oscillation suppression and control device. In the method, a three-phase AC bus voltage Vabc(t) of an access point of the subsynchronous oscillation suppression and control device serves as an input voltage signal which is converted into two phases of orthogonal static coordinate signals Valpha(t) and Vbeta(t) by Clarke conversion, and a phase error signal Pherr is output after the two phases of orthogonal static coordinate signals pass through a digital phase closed loop link; and a generator set shafting torsional vibration mode signal is separated from the phase error signal by a filtering link as the control input signal of the subsynchronous oscillation suppression and control device. In the method, the bus AC voltage of the access point of the subsynchronous oscillation suppression and control device is adopted as a source signal, and the generator set shafting torsional vibration mode signal is obtained by digital phase locked loop and digital processing technologies, and the reliable control input signal can be provided in situ for a device; and the method is relatively lower in cost and easy to implement.

Description

The acquisition methods of a kind of sub-synchronous oscillation inhibition and protective device control input signals

Technical field

The invention belongs to field of power, be specifically related to the acquisition methods of a kind of sub-synchronous oscillation inhibition and protective device control input signals.

Background technology

Sub-synchronous oscillation, be a kind of electrical network and steam turbine in a kind of transient process that is lower than positive energy exchange on one or several frequency of power frequency, the energy exchange of this vibration may be underdamping or negative damping, if negative damping then is unsettled.China generally adopts a little to net transmission of electricity pattern in the thermoelectricity base at present, transmission distance is generally longer, for the stability limit that improves circuit increases ability to transmit electricity, adopt series compensation technology of transmission of electricity and high voltage dc transmission technology, the application of Series Compensation and high voltage dc transmission technology may cause that all many fired power generating unit of sending end face the sub-synchronous oscillation problem.If taking braking measure at every unit near machine is distolateral, project cost is high and control is complicated, thereby need adopt multiple inhibition and safeguard measure to solve the sub-synchronous oscillation problem of thermoelectricity base multimachine in grid side.

The length of thermal power plant Steam Turbine Generator group rotor may be above 40 meters, weight can reach the hundreds of ton, each section of rotor can be regarded the lumped mass piece that plurality of elastic connects as, each mass is in rotation synchronously in the disturbed system, torsional oscillation vibration relative between mass also can take place, comprised a series of torsional modes, the synchronizing frequency that torsion frequency is lower than electrical network is called sub-synchronous oscillation.Practical power systems is in dynamic balance state, and system disturbance all may cause the subsynchronous torsional oscillation oscillatory occurences of the different amplitudes of shaft system of unit.Shaft system of unit is owing to its axle of reasons such as bearing friction, windage is that mechanical system presents the positive damping feature, if sending, unit do not have string benefit device, high voltage dc transmission technology etc. in the system, general and axle is that the subsynchronous hunting of frequency of subsynchronous torsion frequency complementation is the positive damping feature in electrical network, disturbance causes that the subsynchronous torsional oscillation vibration of shaft system of unit presents the positive damping characteristic, and the very fast decay of oscillation amplitude is gone down.In order to improve ability to transmit electricity and efficient, the thermal power plant is sent system and is adopted string to mend device or high voltage dc transmission technology etc., may cause that the sub-synchronous oscillation problem of electric power system, torsional oscillation problem or the generation axle that generator rotor shaft is lasting or even amplification are fatigue loss, can cause the shaft system of unit damage accident under the serious situation.

Thermal power plant Steam Turbine Generator group rotor is made up of steam turbine section and generator section, the steam turbine section is made up of high pressure cylinder, intermediate pressure cylinder and each section of low pressure (LP) cylinder, generator section or contain exciter, as shown in Figure 1, each section formed long elastic shaft system, and 1 is steam turbine high-pressure cylinder among the figure, and 2 is low pressure (LP) cylinder A, 3 is low pressure (LP) cylinder B, and 4 is generator.During the electric power system generation disturbance of generator connecting in parallel with system, can cause the variation of generator electromotive power output, cause that it is the electromagnetic torque disturbance that generator is applied to axle.Shaft system of unit produces mutual torsional oscillation vibration as long elastic system between each section when disturbed, there be N-1 torsional oscillation mode in a N section axle system, and the part model frequency is lower than the synchronized frequency.As if the subsynchronous hunting of frequency with the shafting torsional oscillation mode frequency complementary is non-positive damping feature in electrical network, then disturbance causes that the subsynchronous torsional oscillation vibration of shaft system of unit presents non-positive damping characteristic, the vibration of axle system is kept than large amplitude or increasing oscillation, and causing axle is fatigue loss or damage.

The sub-synchronous oscillation problem becomes a safe operation major issue that jeopardizes electrical network.At present the sub-synchronous oscillation problem there are multiple braking measure and safeguard measure.Sub-synchronous oscillation braking measure near unit is controlled as additional excitation damping; dynamic stability device etc.; protective device such as axle are torsional stress relay and armature supply relay etc.; pass through photoelectric tachometric transducer; Hall speed probe or magnetoelectric tachometric transducer as shown in Figure 1; 5-tachometric survey gear among Fig. 1; 6-gear emboss pit; 7 is induction coil; 8 is permanent magnet; 9 is the air air gap; 10 is magnetic conductive soft iron; 11 is signal conditioning circuit; is axle the signal of telecommunication that rotating speed is converted to alternation, and this signal extremely installs by cable transmission, by filtering; signal condition and employing change digital signal into; be decomposed into the torsional oscillation mode signal through Digital Signal Processing again, as the input signal of controller.

China generally adopts a little to net transmission of electricity pattern in the thermoelectricity base at present, transmission distance is generally longer, for the stability limit that improves circuit increases ability to transmit electricity, adopt series compensation technology of transmission of electricity and high voltage dc transmission technology, the application of Series Compensation and high voltage dc transmission technology may cause that all many fired power generating unit of sending end face the sub-synchronous oscillation problem.If taking braking measure at every unit near machine is distolateral, project cost is high and control is complicated, thereby need adopt multiple inhibition and safeguard measure to solve the sub-synchronous oscillation problem of thermoelectricity base multimachine in grid side.Unit rotor speed measuring-signal is to suppress and the reliable input signal of protective device near machine end sub-synchronous oscillation; and to having the grid side sub-synchronous oscillation of certain distance to suppress and protective device with unit; if adopt unit rotor speed signal as input signal; may face problem: the axle of a plurality of units is that tach signal all needs by the certain distance traffic channel to suppressing and protective device, and the higher and intermediate link of engineering cost reduces the reliability of engineering more.Based on this, exigence those skilled in the art develop a method of measurement that can overcome the sub-synchronous oscillation signal of above-mentioned defective.

Summary of the invention

In order to overcome the above-mentioned defective of prior art; the objective of the invention is to propose that a kind of sub-synchronous oscillation suppresses and the acquisition methods of protective device control input signals, the cost of this method is lower, be easy to realize and can be on the spot provide reliable control input signals for sub-synchronous oscillation inhibition and protective device.

For achieving the above object, the acquisition methods of sub-synchronous oscillation inhibition of the present invention and protective device control input signals is achieved through the following technical solutions:

The acquisition methods of a kind of sub-synchronous oscillation inhibition and protective device control input signals, its improvements are: this method is with the three-phase alternating current busbar voltage V of sub-synchronous oscillation inhibition and protective device access point _Abc(t) as input voltage signal, this input voltage signal is transformed to two-phase quadrature static coordinate signal V through Clarke _α(t), V _β(t), two-phase quadrature static coordinate signal V _α(t) and V _β(t) through digital phase-locked loop link output phase error signal Ph _ErrPhase error signal Ph _ErrIsolate the control input signals of generator set torsional vibration mode signal through the filtering link as sub-synchronous oscillation inhibition and protective device.

Wherein, described digital phase-locked loop link comprises ratio-integral element, integral element and feedback element, and its concrete steps are as follows:

If the synchronized frequency is f ₀=50Hz, synchronous phase angle are β=ω ₀T=2 π f ₀T, the three-phase alternating current busbar voltage is:

$\left\{\begin{array}{c}{v}_a=V_m\sin \left(\mathrm{\β}\right)\\ v_b=V_m\sin (\mathrm{\β}-\frac{2\mathrm{\π}}{3})\\ v_c=V_m\sin (\mathrm{\β}+\frac{2\mathrm{\π}}{3})\end{array}\right.$

Represent with vector form: v _Abc=[v _av _bv _c] ^T

C is a Clarke Clarke transformation matrix, C ^-1Be inverse-transform matrix:

$C=\frac{2}{3}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\\ \frac{1}{2}& \frac{1}{2}& \frac{1}{2}\end{array}\right]$ $C^{-1}=\left[\begin{array}{ccc}1& -\frac{1}{2}& 1\\ -\frac{1}{2}& \frac{\sqrt{3}}{2}& 2\\ -\frac{1}{2}& -\frac{\sqrt{3}}{2}& 1\end{array}\right]$

Vector representation is under the three-phase alternating current busbar voltage static coordinate:

v _αβ0＝[v _α(t)v _β(t)v ₀(t)] ^T

Can obtain by the Clarke conversion that vector is under the ac bus voltage static coordinate

v _αβ0＝Cv _abc＝[V _msin(β)-V _mcos(β)0] ^Tv _abc＝C ^-1v _αβ0

Three-phase alternating current busbar voltage V _Abc(t) as input voltage signal, obtain the phase value θ of input voltage signal through phase-locked loop, pass through the feedback element sin (θ) and the cos (θ) of phase-locked loop again, obtain the feedback signal Vsin (θ) and the Vcos (θ) of these two trigonometric functions, Vsin (θ) and input signal v _α(t) product, Vcos (θ) and input signal v _β(t) product, the sum of products be as the input signal of proportional integral link, the input signal v of ratio-integral element _PIFor:

$v_{\mathrm{PI}}=[V_m\sin \left(\mathrm{\β}\right)-V_m\cos \left(\mathrm{\β}\right)]\left[\begin{array}{c}{V}_m^{-1}\cos \left(\mathrm{\θ}\right)\\ V_m^{-1}\sin \left(\mathrm{\θ}\right)\end{array}\right]=\sin \left(\mathrm{\β}\right)\cos \left(\mathrm{\θ}\right)-\cos \left(\mathrm{\β}\right)\sin \left(\mathrm{\θ}\right)$

Phase-locked loop can accurately be followed the tracks of the phase value of input voltage signal, and three-phase positive sequence voltage signal is θ=π+β through the phase value that phase-locked loop obtains input voltage, and the input signal of ratio-integral element is 0;

The transfer function of ratio-integral element is:

Wherein GP is a proportionality coefficient, and GI is an integral coefficient, and the s Laplacian obtains phase error signal Ph by following formula _Err:

${\mathrm{Ph}}_{\mathrm{err}}=(\mathrm{GP}+\frac{\mathrm{GI}}{s})v_{\mathrm{PI}}+2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="0"\; label="f"\; filenames="HSA00000393172000012.png,HSA00000393172000021.png"\; state="\{\{state\}\}">f</figure-callout>}}_0$

Phase error signal Ph _ErrPass through integral element again Obtain the phase value of input voltage signal

Wherein, described filtering link comprises low-pass filtering, high-pass filtering and bandpass filtering successively, and described low-pass filtering adopts low pass filter, and high pass filter is adopted in described high-pass filtering, and described bandpass filtering adopts band pass filter.

The concrete steps of described filtering link are as follows:

Phase error signal Ph through the output of digital phase-locked loop link _ErrIn include supersynchronous frequency-doubled signal, high-frequency harmonic signal, low frequency oscillations signal and the subsynchronous frequency signal of generator unit shaft system mode, in order finally to isolate the generator set torsional vibration mode signal, at first with phase error signal Ph _ErrThrough as shown in the formula the low pass link, filter out supersynchronous frequency-doubled signal and high-frequency harmonic signal,

$\frac{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HSA00000393172000021.png,HSA00000393172000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}{1+2{\mathrm{\&xi;}}_1\left(\frac{s}{{\mathrm{\&omega;}}_{c1}}\right)+{\left(\frac{s}{{\mathrm{\&omega;}}_{c1}}\right)}^2}$

Wherein, G ₁Be proportionality coefficient, ω _C1Be low pass link corner frequency, ξ ₁Be damping ratio, the s Laplacian;

Secondly through as shown in the formula the high pass link, filter out the low frequency oscillations signal,

$\frac{G_2{\left(\frac{s}{{\mathrm{\&omega;}}_{c2}}\right)}^2}{1+2{\mathrm{\&xi;}}_2\left(\frac{s}{{\mathrm{\&omega;}}_{c2}}\right)+{\left(\frac{s}{{\mathrm{\&omega;}}_{c2}}\right)}^2}$

Wherein, G ₂Be proportionality coefficient, ω _C2Be high pass link corner frequency, ξ ₂Be damping ratio, the s Laplacian;

Once more through as shown in the formula the logical link of band, isolate the subsynchronous frequency signal of generator unit shaft system mode of appointment,

$\frac{G_3\left(\frac{s}{{\mathrm{\&omega;}}_{c3}}\right)}{1+2{\mathrm{\&xi;}}_3\left(\frac{s}{{\mathrm{\&omega;}}_{c3}}\right)+{\left(\frac{s}{{\mathrm{\&omega;}}_{c3}}\right)}^2}$

G wherein ₃Be proportionality coefficient, ω _C3For being with logical link corner frequency, ξ ₃Be damping ratio, the s Laplacian;

Through the subsynchronous frequency signal that above-mentioned filtering link obtains, can reflect the torsional oscillation amplification level of the generator set torsional vibration mode signal that electrical distance is nearer, the component of voltage frequency that is reflected in the subsynchronous frequency signal of grid side is f _d=50-f _sHertz, wherein f _dBe the component of voltage frequency of subsynchronous frequency signal, f _sBe the frequency of generator set torsional vibration mode signal, then [the 50-f that contains in the phase error signal _d]=[50-(50-f _s)]=f _sHertz, the generator set torsional vibration mode signal that is obtained exactly.

The invention has the beneficial effects as follows:

For the stability limit that improves circuit increases ability to transmit electricity; series compensation technology of transmission of electricity or high voltage dc transmission technology transmission of electricity pattern are generally adopted in the thermoelectricity base; may cause that many fired power generating unit of sending end face the sub-synchronous oscillation problem, need adopt the combination of multiple inhibition and safeguard measure to solve the sub-synchronous oscillation problem in thermoelectricity base.Sub-synchronous oscillation suppresses and protective device can be installed near distolateral installation of machine and grid side; the shaft system of unit tach signal is that the distolateral sub-synchronous oscillation of reliable machine suppresses and the protective device control input signals; and to the grid side sub-synchronous oscillation suppress and protective device as if taking same quadrat method; the a plurality of units in thermoelectricity base need insert signal by longer communication channel; project cost is higher, coordinates the control complexity and may reduce reliability.The present invention proposes to adopt sub-synchronous oscillation to suppress and the bus alternating voltage of protective device access point is a source signal; obtain shaft system of unit torsional oscillation mode signal by digital phase-locked loop and digital processing technology; cost is lower and be easy to realization, can provide reliable control input signals for device on the spot.

Description of drawings

Fig. 1 is thermoelectric generator group axle system and a tachometric survey schematic diagram in the prior art;

Fig. 2 is the structural representation of digital phase-locked loop (PLO), and PI is ratio-integral element among the figure, and GP is a proportionality coefficient, and GI is an integral coefficient, ω _oBe the power frequency synchronous angular velocity;

Fig. 3 is phase error signal is isolated the torsional oscillation mode signal by the filtering link a view;

Fig. 4 is that generator shaft is rotating speed and synchronous speed aberration curve figure;

Fig. 5 is a bus three-phase alternating voltage oscillogram;

Fig. 6 is digital phase-locked loop output voltage phase waveform figure;

Fig. 7 is a phase error signal oscillogram in the digital phase-locked loop;

Fig. 8 is the spectrum analysis figure of phase error signal in the digital phase-locked loop;

Fig. 9 is that existing axle is that tach signal mode is mode curve comparison diagram with adopting digital phase-locked loop to measure axle;

Figure 10 is that existing axle is that tach signal mode is the local curve comparison diagram of mode with adopting digital phase-locked loop to measure axle;

Embodiment

Be further described in detail below in conjunction with the acquisition methods of accompanying drawing sub-synchronous oscillation inhibition of the present invention and protective device control input signals.

The acquisition methods of sub-synchronous oscillation inhibition of the present invention and protective device control input signals is with the three-phase alternating current busbar voltage V of sub-synchronous oscillation inhibition and protective device access point _Abc(t) as input voltage signal, this input voltage signal is transformed to two-phase quadrature static coordinate signal V through Clarke _α, V _β, two-phase quadrature static coordinate signal V _α(t) and V _β(t) through digital phase-locked loop link output phase error signal Ph _ErrPhase error signal Ph _ErrIsolate the control input signals of generator set torsional vibration mode signal through the filtering link as sub-synchronous oscillation inhibition and protective device.The digital phase-locked loop link comprises ratio-integral element, integral element and feedback element; The filtering link comprises low-pass filtering, high-pass filtering and bandpass filtering, and low-pass filtering adopts low pass filter, and high pass filter is adopted in high-pass filtering, and bandpass filtering adopts band pass filter.

Phase-locked loop is a common component in the control system, adopts feedback principle, when the frequency of pll output signal equates with the frequency of input signal, and the difference that the phase place of two signals is maintained fixed.Be illustrated in figure 2 as digital phase-locked loop (PLO) structural representation, as the power-frequency voltage synchronism link, input signal is ac bus three-phase voltage V in high voltage dc transmission technology (HVDC) and flexible ac transmission technology (FACTs) _Abc(t), be transformed to two-phase quadrature static coordinate signal V through Clark _{α β}(t), through ratio-integral element (PI link) and feedback element regulating action, output AC voltage signal V _A(t) phase value θ.

Because three-phase alternating current busbar voltage V _Abc(t) containing time frequency component of voltage in is:

$\left\{\begin{array}{c}{\mathrm{\&Delta;v}}_{\mathrm{sa}}\left(t\right)=V_s\cos \left(2\mathrm{\&pi;}{f}_{d}t\right)\\ {\mathrm{\&Delta;v}}_{\mathrm{sb}}\left(t\right)=V_s\cos (2\mathrm{\&pi;}{f}_{d}t-2/3\mathrm{\&pi;})\\ {\mathrm{\&Delta;v}}_{\mathrm{sc}}\left(t\right)=V_s\cos (2\mathrm{\&pi;}{f}_{d}t+2/3\mathrm{\&pi;})\end{array}\right.---\left(1\right)$

$\left\{\begin{array}{c}{\mathrm{\&Delta;v}}_{\mathrm{sa}}\left(t\right)=V_s\cos \left(2\mathrm{\&pi;}{f}_{d}t\right)\\ {\mathrm{\&Delta;v}}_{\mathrm{sb}}\left(t\right)=V_s\cos (2\mathrm{\&pi;}{f}_{d}t-2/3\mathrm{\&pi;})\\ {\mathrm{\&Delta;v}}_{\mathrm{sc}}\left(t\right)=V_s\cos (2\mathrm{\&pi;}{f}_{d}t+2/3\mathrm{\&pi;})\end{array}\right.---\left(2\right)$

F in the formula _dBe inferior frequency electric voltage frequency, so the phase error signal Ph of digital phase-locked loop link output _ErrIn contain with busbar voltage in the frequency signal of the frequency complementary of voltage time frequently.If time frequency component of voltage " positive sequence is to weighing " form shown in following formula (1), then phase error signal Ph in the three-phase bus voltage _ErrIn contain frequency for (f ₀-f _d) and 2 (f ₀-f _d) signal component, wherein f ₀Be the synchronized electric voltage frequency; If time frequency component of voltage " negative phase-sequence is to weighing " form shown in following formula (2), then phase error signal Ph in the three-phase alternating voltage _ErrIn contain frequency for (f ₀+ f _d) and 2 (f ₀+ f _d) signal component, the ratio that supersynchronous frequency multiplication component accounts for is less;

Because of system disturbance produces " symmetry " inferior frequency voltage/current component at generator machine end, because the elements such as circuit of real system are asymmetric and HVDC or FACTs electronic power switch action non-linear process, time frequency voltage may contain " asymmetric " component in ac bus voltage, thereby contains (f in power frequency synchronism link phase-locked loop _s± f _d) and 2 (f _s± f _d) the frequency series of signals.Dimension frequency component of voltage exists and causes that power frequency is asymmetric in addition, forms negative phase-sequence (100Hz) component, and subsynchronous frequency signal component proportion is greater than other components.

Suppose that unit shafting torsional oscillation mode frequency is f _sHertz, then being reflected in the subsynchronous component of voltage frequency of grid side is f _d=50-f _sHertz, through the phase-locked loop link, wherein will contain [50-f in the error phase signal _d]=[50-(50-f _s)]=f _sHertz, obtained exactly shaft system of unit torsional oscillation mode signal.

Time frequency component of voltage frequency sum in the subsynchronous torsional oscillation mode frequency of shaft system of unit and the electrical network is the synchronized frequency, the phase error signal Ph of digital phase-locked loop _ErrIn the component of voltage frequency sum time frequently that is lower than in the signal component frequency of synchronizing frequency and the electrical network also be the synchronized frequency, thereby Ph _ErrIn subsynchronous signal frequency equate that with the subsynchronous torsional oscillation mode frequency of shaft system of unit this signal is the same with the shaft system of unit tach signal can to reflect the torsional oscillation level of axle system.As shown in Figure 4, Ph _ErrSignal obtains the generator set torsional vibration mode signal through filtering, can also carry out mode to the mode signal as required and decompose.Can be used as with unit the sub-synchronous oscillation inhibition of certain distance and the control input signals of protective device are arranged.

Embodiment

Be example with certain many large electric power plant unit in coal electricity base by remote high-power the transmitting electric power of high voltage direct current transmission project, through studies show that, coal electricity base is in the isolated island system mode, the unit that the is incorporated into the power networks back of boosting directly is connected with high voltage direct current transmission converting plant ac bus, electrical couplings is tight, the sub-synchronous oscillation problem takes place in start more after a little while, i.e. shaft system of unit low order torsional oscillation mode generation amplification phenomenon of torsional vibration may cause the tired or damage of axle system.Need take the sub-synchronous oscillation braking measure to solve shaft system of unit torsional oscillation instability problem.

Sub-synchronous oscillation suppresses and protective device needs can characterize the sub-synchronous oscillation characteristic signals as input control signal, measures the real-time rotating speed of shaft system of unit by speed probe as shown in Figure 1, has directly reflected the shafting torsional oscillation characteristic as shown in Figure 4.When the input control signal of net lateral inhibition and protective device adopted this method, the axle of a plurality of units was that tach signal all needs extremely to install by the certain distance traffic channel, and engineering cost is higher and intermediate link is many, reduces the reliability of engineering.

For example coal electricity base unit and converting plant connected system mode, shaft system of unit is 4 mass models, wherein low order torsional oscillation mode frequency is 12.72Hz.Adopt converting plant three-phase bus alternating voltage V as shown in Figure 5 _Abc(t) as input signal, as shown in Figure 2, this input signal is transformed to two-phase quadrature static coordinate signal V through Clarke _α(t) and V _β(t), V _α(t) and V _β(t) with the feedback signal sum of products, and process proportional plus integral control link (GP=2000.0, GI=1.0), output AC voltage signal V _A(t) phase value θ as shown in Figure 6, described phase value θ forms feedback signal through the trigonometric function link, forms the digital phase-locked loop closed loop controlling structure.

As shown in Figure 7, the proportional plus integral control link output phase error signal Ph of digital phase-locked loop _Err, signal spectral analysis as shown in Figure 8.This signal is through low pass link (G ₁=1.0, ω _C1=219.9, ξ ₁=0.5) high pass link (G is passed through in conversion again ₂=1.0, ω _C2=62.8, ξ ₂=0.5) conversion, known shaft system of unit low order torsional oscillation mode frequency is 12.72Hz, the high pass link is handled the back signal through the logical link (G of band ₃=12.0, ω _C3=79.9, ξ ₃=0.15) shaft system of unit single order mode (12.72Hz) torsional vibration signals is isolated in conversion.As Fig. 9 and Figure 10 for existing directly measure behind the shaft system of unit rotating speed model analysis and bus three-phase alternating voltage through the phase-locked loop measurement after model analysis comparison of wave shape figure.As seen from the figure; the bus three-phase alternating voltage is through the phase-locked loop link; wherein to have comprised the fired power generating unit axle be mode torsional oscillation level to phase error signal; consistent through obtaining the mode signal after the filtering signal processing again with model analysis behind the direct measurement shaft system of unit rotating speed, can be used as the control input signals of subsynchronous restraining device and protective device.

Should be noted that at last: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although the present invention is had been described in detail with reference to the foregoing description, those of ordinary skill in the field are to be understood that: still can make amendment or be equal to replacement the specific embodiment of the present invention, and do not break away from any modification of spirit and scope of the invention or be equal to replacement, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (4)

1. a sub-synchronous oscillation suppresses and the acquisition methods of protective device control input signals, and it is characterized in that: this method is with the three-phase alternating current busbar voltage V of sub-synchronous oscillation inhibition and protective device access point _Abc(t) as input voltage signal, this input voltage signal is transformed to two-phase quadrature static coordinate signal V through Clarke _α(t), V _β(t), two-phase quadrature static coordinate signal V _α(t) and V _β(t) through digital phase-locked loop link output phase error signal Ph _ErrPhase error signal Ph _ErrIsolate the control input signals of generator set torsional vibration mode signal through the filtering link as sub-synchronous oscillation inhibition and protective device.

2. the acquisition methods of sub-synchronous oscillation inhibition as claimed in claim 1 and protective device control input signals, it is characterized in that: described digital phase-locked loop link comprises ratio-integral element, integral element and feedback element, and its concrete steps are as follows:

If the synchronized frequency is f ₀=50Hz, synchronous phase angle are β=ω ₀T=2 π f ₀T, the three-phase alternating current busbar voltage is:

$\left\{\begin{array}{c}{v}_a=V_m\sin \left(\mathrm{\&beta;}\right)\\ v_b=V_m\sin (\mathrm{\&beta;}-\frac{2\mathrm{\&pi;}}{3})\\ v_c=V_m\sin (\mathrm{\&beta;}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right.$

Represent with vector form: v _Abc=[v _av _bv _c] ^T

C is a Clarke Clarke transformation matrix, C ^-1Be inverse-transform matrix:

$C=\frac{2}{3}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\\ \frac{1}{2}& \frac{1}{2}& \frac{1}{2}\end{array}\right]$ $C^{-1}=\left[\begin{array}{ccc}1& -\frac{1}{2}& 1\\ -\frac{1}{2}& \frac{\sqrt{3}}{2}& 2\\ -\frac{1}{2}& -\frac{\sqrt{3}}{2}& 1\end{array}\right]$

The three-phase father flows that vector representation is under the busbar voltage static coordinate:

v _αβ0＝[v _α(t)v _β(t)v ₀(t)] ^T

Can obtain by the Clarke conversion that vector is under the ac bus voltage static coordinate

v _αβ0＝Cv _abc＝[v _msin(β)-v _mcos(β)0] ^Tv _abc＝C ^-1v _αβ0

Three-phase alternating current busbar voltage V _Abc(t) as input voltage signal, obtain the phase value θ of input voltage signal through phase-locked loop, pass through the feedback element sin (θ) and the cos (θ) of phase-locked loop again, obtain the feedback signal Vsin (θ) and the Vcos (θ) of these two trigonometric functions, Vsin (θ) and input signal v _α(t) product, Vcos (θ) and input signal v _β(t) product, the sum of products be as the input signal of ratio-integral element, the input signal v of ratio-integral element _PIFor:

$v_{\mathrm{PI}}=[V_m\sin \left(\mathrm{\&beta;}\right)-V_m\cos \left(\mathrm{\&beta;}\right)]\left[\begin{array}{c}{V}_m^{-1}\cos \left(\mathrm{\&theta;}\right)\\ V_m^{-1}\sin \left(\mathrm{\&theta;}\right)\end{array}\right]=\sin \left(\mathrm{\&beta;}\right)\cos \left(\mathrm{\&theta;}\right)-\cos \left(\mathrm{\&beta;}\right)\sin \left(\mathrm{\&theta;}\right)$

Phase-locked loop can accurately be followed the tracks of the phase value of input voltage signal, and three-phase positive sequence voltage signal is θ=π+β through the phase value that phase-locked loop obtains input voltage, and the input signal of ratio-integral element is 0;

The transfer function of ratio-integral element is:

Wherein GP is a proportionality coefficient, and GI is an integral coefficient, and s draws the pula operator that breaks, and obtains phase error signal Ph by following formula _Err:

${\mathrm{Ph}}_{\mathrm{err}}=(\mathrm{GP}+\frac{\mathrm{GI}}{s})v_{\mathrm{PI}}+2\mathrm{\&pi;}{f}_0$

Phase error signal Ph _ErrPass through integral element again

Obtain the phase value of input voltage signal

3. the acquisition methods of sub-synchronous oscillation inhibition as claimed in claim 1 and protective device control input signals; it is characterized in that: described filtering link comprises low-pass filtering, high-pass filtering and bandpass filtering successively; described low-pass filtering adopts low pass filter; high pass filter is adopted in described high-pass filtering, and described bandpass filtering adopts band pass filter.

4. the acquisition methods of sub-synchronous oscillation inhibition as claimed in claim 3 and protective device control input signals, it is characterized in that: the concrete steps of described filtering link are as follows:

Phase error signal Ph through the output of digital phase-locked loop link _ErrIn include supersynchronous frequency-doubled signal, high-frequency harmonic signal, low frequency oscillations signal and the subsynchronous frequency signal of generator unit shaft system mode, in order finally to isolate the generator set torsional vibration mode signal, at first with phase error signal Ph _ErrThrough as shown in the formula the low pass link, filter out supersynchronous frequency-doubled signal and high-frequency harmonic signal,

$\frac{G_1}{1+2{\mathrm{\&xi;}}_1\left(\frac{s}{{\mathrm{\&omega;}}_{c1}}\right)+{\left(\frac{s}{{\mathrm{\&omega;}}_{c1}}\right)}^2}$

Wherein, G ₁Be proportionality coefficient, ω _C1Be low pass link corner frequency, ξ ₁Be damping ratio, the s Laplacian;

Secondly through as shown in the formula the high pass link, filter out the low frequency oscillations signal,

$\frac{G_2{\left(\frac{s}{{\mathrm{\&omega;}}_{c2}}\right)}^2}{1+2{\mathrm{\&xi;}}_2\left(\frac{s}{{\mathrm{\&omega;}}_{c2}}\right)+{\left(\frac{s}{{\mathrm{\&omega;}}_{c2}}\right)}^2}$

Wherein, G ₂Be proportionality coefficient, ω _C2Be high pass link corner frequency, ξ ₂Be damping ratio, the s Laplacian;

Once more through as shown in the formula the logical link of band, isolate the subsynchronous frequency signal of generator unit shaft system mode of appointment,

$\frac{G_3\left(\frac{s}{{\mathrm{\&omega;}}_{c3}}\right)}{1+2{\mathrm{\&xi;}}_3\left(\frac{s}{{\mathrm{\&omega;}}_{c3}}\right)+{\left(\frac{s}{{\mathrm{\&omega;}}_{c3}}\right)}^2}$

G wherein ₃Be proportionality coefficient, ω _C3For being with logical link corner frequency, ξ ₃Be damping ratio, the s Laplacian;

Through the subsynchronous frequency signal that above-mentioned filtering link obtains, can reflect the torsional oscillation amplification level of the generator set torsional vibration mode signal that electrical distance is nearer, the component of voltage frequency that is reflected in the subsynchronous frequency signal of grid side is f _d=50-f _sHertz, wherein f _dBe the component of voltage frequency of subsynchronous frequency signal, f _sBe the frequency of generator set torsional vibration mode signal, then [the 50-f that contains in the phase error signal _d]=[50-(50-f _s)]=f _sHertz, the generator set torsional vibration mode signal that is obtained exactly.

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